Pickling and cleaning of metal



252 COMPOSITIONS. i i i l i i fei ned July 2, 1929. 1,719,649 UNITEDSTATES PATENT OFFICE.

GEORGE D. CHAMBERLAIN, OF ASHLAND, KENTUCKY, ASSIGNOR TO R. T.VANDERIBILT COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OFYORK.

PICKLING AND CLEANING OF METAL.

No Drawing. Application filed January 11, 1927. Serial No. 160,525.

This invention relates to the pickling and hyde onthe condfil sate ofacetaldehyde with cleaning of metals, and particularly to the anil 1n,.. among other'condensation products pickling of iron or steel, toremove scale Tn'ay be mentioned the condensation product therefrom,although the invention is of more of heptaldehyde with anilin, offormaldeor less general application to the cleaning or h'yde with anilinor with o-toluidine, or furpi'ckling of metals such as iron or steel forfural' with diethyharnineor with diphenylthe removal of oxides or scaletherefrom. guan'idine, etc. l

The pickling or cleaning of iron or steel ""The'acid pickling baths withwhich the is commonly effected by means of acid pickagents mentioned areused may be acid baths ling or cleaning baths which dissolve the Such asare commonly employed for pickling scale or oxide from the metal. Thepickling or cleaning iron and steel, containing for baths commonlyemployed are acid baths example, about 10% of sulfuric acid. Such whichoften attack the metal as well as the baths are gradually impoverishedby the acetaldehyde, butyraldehyde, hep t a l lehyd:e, practice. Forexample, the pickling can be scale. This action on the metal isundesirable action of the acid in removing the scale or andobjectionable, involving not only excesrust and their content of ferroussulfate in sive. consumption of acids, but also corrosion creases untilthe bath becomes too weak or or dissolving of metal and tending to givea too concentrated in ferrous sulfate for furrough or pitted surface.ther use. Instead of usin sulfuric acid The present invention providesan imbaths, other acid baths can e used, includproved bath for picklingor cleaning metals ing acid sulfate baths. and also an improved processof pickling or The amountof the condensation product cleaning the metalin which the acid pickling added to the bath for carrying out thepickbath has incorporated therein a small amount ling or cleaningoperation can be varied. In f g pgganic general, only a small amount ofthe condenamine WlWe. sation product is required, for example, a ruaetound that the addition of a small small fraction of one per cent. In thecase amount of a suitable condensation product of the condensationproduct of aldol and of an aldehyde with an amine prevents oralpha-naphthylamine, for example, about retards or inhibits the attackof the acid two pounds of the condensation product can pickling bath onthe metal without interbe employed for each ton of 60 degree acid feringwith the removal of scale or oxide by used in the pickling bath. Asimilar or somethe acid bath and leaves the surface of the Whatincreased amount of the condensation cleaned metal in. better condition.product of aldol wit-h diphenylguanidine can The agents which are addedto the cleanbe similarly used. The condensation product ing or picklingbath, according to the present employed should be one which is stableand invention, include various products of ami v IMF yes. tent in theacid bath. these ma e mentioned condensation prod- The carrying out ofthe pickling or clean- :uct s of various"aldehydsfsuch as aldol, ingoperation may be the same as in ordinary furfural, benzaldehyde, etc.with amines. carried out continuously by passing the mai Certaincondensation products'of aldol with terial to be pickled, such as wireor sheets,

amines are particularly advantageous, such through a number of baths ina regulated the condensation product of ald ol with manner; or byimmersing the article to be l phwpli thylamfnband with certainguaiipickled in the pickling bath for a suitable idines such asdiphenylguanidine and certain period of time. The temperature of thebath 7 other di-substituted guanid'ine's. Cond'ensa can be varied,ordinarily being around 150 tion products of guanidines with otheraldeto 180 F. The pickling bath may be re-- hydes can also be used, aswell as condensation plenished by the addition of further amountsproducts of other amines with aldehydes. of acid until the iron sulfatereaches too great For example, the condensation products of aconcentration.

anilin with acetaldehyde, including the con- The addition of thecondensation product densates produced both in presence and in to thebath prevents or retards or inhibits absence of acid, can be used, orthe product the action of the acid bath on the metal withformed by thefurther action gf formaldeout interfering with the removal of scale or 1Examiner.

condens tion does not decompose to any objectionable exoxide. Theformation of hydrogen by the action of the acid bath on the metal isalso reduced and the evolution of acid mist or fumes also greatlyreduced. There is also a saving in the acid as Well as a protection ofthe metal. The reduced amount of action of the acid on the metal and thereduction in .amount of hydrogen produced correspondtection of the metalfrom attack, etc., which materially improve the pickling and cleaningoperation.

I claim:

1. The method of cleaning or pickling metals which comprises subjectingthe same to a non-oxidizing mineral acid pickling or cleaning bath andinhibiting the chemical action of the acid on the metal withoutinterfering with the removal of scale or oxide, and therecondensationproduct of an aldehyde with an amine.

2. The method of cleaning or pickling metals which comprises subjectingthe same to a non-oxidizing mineral acid pickling or cleaning bath andinhibiting the chemical action of the acid on the metal withoutinterfering with the removal of scale or oxide, and thereby reducing theformation of hydrogen and the production of acid fumes and effecting aneconomy in the acid consumed, by incorporating in the acid bath a smallamount of a condensation product of aldol with an amine.

3. The method of cleaning or pickling metals which comprises subjectingthe same to a non-oxidizing mineral acid pickling or cleaning bath andinhibiting the chemical action of the acid on the metal withoutinterfering with the removal of scale or oxide, and thereby reducing theformation of hydrogen and the production of acid fumes and effecting aneconomy in the acid consumed, by incorporating in the acid bath a smallamount of a condensation product of aldol with alphanaphthylamine.

4. The method of pickling or cleaning iron or steel which comprisessubjecting the same to an acid pickling bath containing sulfuric acidand inhibiting the chemical action of the acid on the metal withoutinterferin with the removal of scale or oxide, and t ereby 5. The methodof pickling or cleaning iron or steel which comprises subjecting thesame to an acid pickling bath containing sulfuric acid and inhibitingthe chemicaI action of the acid on the metal without interfering withthe removal of scale or oxide, and thereby reducing the formation ofhydrogen and the production of acid fumes and effecting an economy inthe acid consumed, by incorporating in the acid bath a small fraction ofone percent of a condensation product of aldol with an amine.

6. The method of picklin or cleaning iron or steel which comprises sujecting the same to an acid pickling bath containing sulfuric acid andinhibiting the chemical action of the acid on the metal withoutinterfering with the removal of scale or oxide, and thereby reducing theformation of hydrogen and the production of acid fumes and effecting aneconomy in the acid consumed, by incorporating in the acid bath a smallfraction of one percent of a condensation product of aldol with alphanapththylamine.

7. A non-oxidizing mineral acid bath for pickling or cleaning metalswhich contains a small amount of a condensation product of an aldehydewith an amine.

8. A non-oxidizing mineral acid bath forpickling or cleaning metalswhich contains a fraction of one percent of the condensation product ofaldol with an amine.

9. A bath for cleaning or pickling metals which contains sulfuric acidand a small amount of a condensation product of an aldehyde with anamine.

10. A bath for cleaning or pickling iron or steel which containssulfuric acid and a fraction of one percent of a condensation product ofaldol with alphanaphthylamine.

11. A bath for cleaning or pickling metals which contains sulfuric acidand a condensation product of aldol with alphanaphthylamine.

12. A non-oxidizing mineral acid bath for pickling or cleaning metalswhich contains a condensation product of aldol with an amine.

13. A non-oxidizing mineral acid bath for pickling or cleaning metalswhich contains a condensation product of aldol with alphanaphthylamine.

In testimony whereof I afiix my signature.

GEORGE D. CHAMBERLAIN.

